This section provides background information related to the present disclosure which is not necessarily prior art.
Engine assemblies may incorporate the use of turbochargers to compress the air flowing into the engine to provide a greater amount of air to each cylinder. In order to compress the air flow into the engine, the turbocharger uses exhaust flow from the engine to spin a turbine, which in turn spins an air pump (or compressor). Many turbochargers are provided with a wastegate which acts as a valve to divert exhaust gases away from the turbine wheel in a turbocharged engine system in order to regulate the turbine speed. A wastegate is usually controlled by an actuator. A wastegate is normally closed and is held shut by the actuator. When a preset pressure limit is exceeded, the actuator progressively opens the wastegate allowing exhaust flow to bypass the turbine, thus regulating manifold boost pressure. A turbocharger wastegate actuator is selected or engineered for specified boost level and turbine inlet pressure. Precise control of boost near the closed wastegate positions is an ongoing challenge often addressed through wastegate design rather than the actuator design.
Accordingly, it is desirable in the art to provide an improved wastegate actuator to accurately control the resolution and torque output of the wastegate at a near closed position.
A vehicle powertrain includes an engine having an air intake system and an exhaust system. A turbocharger includes a turbine section connected to the exhaust system and a compressor section connected to the air intake system. A wastegate is disposed in the exhaust system and movable between an open and a closed position by an actuator system. The actuator system includes a gear mechanism for moving the wastegate from a closed to an open position and including a pair of noncircular gears.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.